Skip to main content

Algebraic Geometry: Barth Sextic

Barth Sextic - a degree-6 algebraic surface with 65 ordinary double points, the maximum number possible for a sextic in three-dimensional space.










Distance Calculus - Student Reviews

Karen N.★★★★★
Posted: Feb 28, 2020
Courses Completed: Calculus I, Calculus II
Awesome classes! I was really weak with Calculus, so I retook Calc 1 and kept going into Calc 2. I feel like I finally understood Calculus. The finals were pretty thorough, but not nearly as stressful as the blue book exams. I highly recommend these courses!
Transferred Credits To: Various
Jenny Zuercher★★★★
Posted: May 18, 2025
Courses Completed: Precalculus, Calculus II
Dr. Curtis's courses are very difficult, but they are definitely worth it! I took Calculus 2 from Dr. Curtis in my senior year of high school and went into a combined Calculus 2 and Calculus 3 course my first year of college. This course prepared me, and I found that I already knew much of the Calculus 3 coursework. The most difficult part of these courses, in my opinion, is pacing yourself. If you can keep yourself on track, then you are all good to go!
Email: jenz2.home@icloud.com
Transferred Credits To: University of Iowa
Joe★★★★★
Posted: Jan 13, 2020
Courses Completed: Calculus II
This is the most interactive and productive online course I have ever taken. I had taken calculus before but never understood some of the underlying concepts until I took this course.
If you want to really learn calculus in a way that will stay with you for the rest of your life, take this course.
Transferred Credits To: The college of New Jersey
M M.★★★★★
Posted: Feb 8, 2026
Courses Completed: Precalculus, Calculus I
The courses were excellent. Very flexible and engaging and the platform offers a lot of upper-level courses. Dr. Curtis is an outstanding professor and very responsive. I would take again.
Transferred Credits To: None yet
Tanja B.★★★★★
Posted: Jan 28, 2026
Courses Completed: Calculus I
After two failed attempts at my university, this course helped me understand Calculus. The live maths tool along with Dr. Curtis were especially helpful, allowing me to visualize concepts and expand my understanding. The explanations were clear, the examples practical, and I could learn at my own pace, which built my confidence. Thank you.
Transferred Credits To: University of Namibia
Henry F.★★★★★
Posted: Dec 18, 2025
Courses Completed: Differential Equations
Transferred Credits To: Saint Joseph High School
Video Player